Low-cost and easily replicable apparatus: an Arduino controlled device for educational activities focused on measuring Brewster’s angle

In this work, we report the development of a low-cost Arduino-controlled device for didactic activities in light polarization. The main body of the prototype was designed and produced using laser-cut medium density fibreboard parts, including gears and pulleys. As a light source and detector, a 532 nm laser pointer and a light dependent resistor were used, respectively. The moving parts (light source and detector) are controlled using a stepper motor (28BYJ-48) with the ULN2003 driver. The apparatus was tested with glass and plastic (polystyrene) slides. The results show that the prototype can distinguish between parallel and perpendicular polarization (to the plane of incidence). In addition, it is demonstrated that the prototype can be satisfactorily applied to determine the Brewster’s angle, even for solids with close refractive indexes.

A Novel Distal Interlocking Screw Guidance System Using a Laser Pointer and a Mechanical Fine-Adjustment Device

In minimally invasive bone fracture reduction surgery, broken femur bones are firmly fixed to a metallic intramedullary nail (IMN) after they are properly aligned. One of the greatest challenges of this process is that surgeons cannot directly see holes on the IMN, which increases the difficulty of the procedure and results in the requirement of taking a large number of X-ray images to find the location and direction of holes. We propose a novel distal interlocking screw guidance system that consists of a parallel guidance system using a laser pointer (PGSLP) and a mechanical fine-adjustment device (FAD). The PGSLP is used to make the planes of the C-arm and FAD parallel. The FAD is used to concentrically align the IMN hole with the guiding hole. The performance of the proposed device was evaluated by a series of experiments. The tilted angle error between the C-arm and FAD was measured to be 1.24 ± 0.715°. The translational error between the IMN hole and guiding hole was measured to be 0.378 ± 0.120 mm. Since the proposed guiding system is simple, cost-effective, and accurate, we expect it will soon be used in real operations.

How Much Money Do You Need to Feel Taller? Impact of Money on Perception of Body Height

Body height is considered to be one of the most important reproductive signals. However, there are only a few publications on what influences the sense of whether we assess ourselves as tall or short. In the present contribution, the psychological impact of money on the evaluation of a person’s own height was tested. We performed two experimental studies in which the respondents had contact with different amounts of money and were asked to evaluate their body height with the use of a laser pointer. The first experiment (N = 61) showed that contact with money significantly increased subjective height evaluation, and the effect was independent of participants’ real body height. The second experiment (N = 120) replicated the effect of money manipulation. Moreover, it was shown that higher amounts of money increased one’s own height estimation more than smaller amounts. Our research shows that money can be used for building one’s social position, which is an attractiveness signal that can influence one’s own height evaluation.

Clinical cases of laser-induced macular damage in children

Purpose: To study the features of the clinical and functional state of the eyes in children after laser damage to the retina. Material and methods: We examined six patients who incurred retinal photodamage (nine eyes) after using a laser pointer. Results: It was shown that laser-induced damage to the macula led to a decrease in vision in five of the nine eyes, which correlated with changes in the parameters of the rhythmic and macular electroretinogram. The main pathognomonic symptom of photo damage to the macula is the presence of signs of local destruction of the pigment epithelium and the ellipsoid zone of the retina, according to optical coherence tomography (OCT). In two cases, after a macular burn, a neovascular membrane formed, which led to an irreversible decrease in vision. Conclusion: Uncontrolled use of household laser devices (pointers) by children can lead to severe visual impairment. For this reason, the main priority should be prevention, conducting active sanitary and educational work, informing teachers, parents, and children about the potential harm, and timely detection and treatment of retinal photodamage.